U.S. Pat. No. 3,899,807 Sovish et al discuss in detail various prior art approaches to the application of coverings to endless bodies or other difficult to cover shapes. In covering effectively endless electrical cables it has been a common practice to wrap a sheet of heat recoverable plastic about the cable mechanically join the edges of the sheet to form a sleeve and heat the sleeve to cause it to shrink down snuggly around the cable.
Sovish suggests differentially irradiating a plastic material so as to cross link the main body of the sheet to render it heat shrinkable while not irradiating the edges so as to render such heat sealable. Such an approach is cumbersome and uneconomical.
The term "heat sealable" refers to materials that may be bonded by heat generated by chemical and electrical action or mechanical action such as ultra-sonic heating.
The term "heat shrinkable" refers to any material that may be non-destructably reduced in size by heating. In general in the context in which employed in this application the term refers to a cross linked plastic which has been heated above its crystalline melt temperature, stretched and then cooled so as to retain its stretched dimensions. Thereafter upon heating above its crystalline melt temperature the sheet will recover approximately to its original size.